Containers, e.g. PET bottles, have a contact area that is made spherically domed so that the containers can effectively roll against each other around a circumferential track, i.e. on a “rolling ring.” With glass bottles, this can be recognized in the event of reuse of the bottle, for example, by the presence of a wear ring that is noticeably lighter than its surroundings. With PET bottles, “rolling rings” of this kind can be arranged not only in the top area but also in the base area.
In detail, the trading unit is made, for example, in such a way that the containers are supplied upright on a transport level of a conveyor and with their container axes oriented in a vertical direction or in a substantially vertical direction in a mass transport or in a wide container flow. Within the container flow, distinctive features and/or decorative characteristics are randomly oriented. This wide container flow is then converted into a plurality of single-track container flows by division into lanes.
The separation of the containers to form the subsequent trading unit or its container groups from the single-track container flows is carried out in further process stages. This includes combining the necessary number of containers in into a compressed container group in which a plurality of lateral or circumferential surfaces of the containers, i.e. the contact or touching surfaces, lie against each other, and connecting the containers in each container group into a compact and solid or stable trading unit.
It is known to combine items to form an item group by the use of shrink film A disadvantage that arises with this method is that the hear required for shrink-wrapping of the film raises costs.
It has already been proposed that transportable trading units be made by strapping containers together using a strapping, which is typically a loop that reaches around the container group.
A disadvantage of strapping is that the first removal of a container from such a trading unit causes the remaining containers in the trading unit to no longer be held together by the strapping. This occurs not only where the strapping is severed or cut, but also when a single container is removed from the trading unit without cutting through the strapping.
Furthermore, there is always the danger, when transporting trading units of this kind on a conveyor belt, that cylindrical or largely cylindrical items, such as cans, bottles or containers, can adopt a nesting position, i.e. slip into the gap of the neighboring row, as a result of vibration, jolts etc. To prevent this, with known trading units, a very high tension needs to be applied to the strapping.
Also known is application of adhesive agent on containers in narrow areas or rows, wherein adjacent areas that are not provided with adhesive agent allow the pack to be gripped for carrying purposes and wherein the containers stick to each other at those places that have adhesive. Also known is application of adhesive coupled with use of a shrink film.